1. Field of the Invention
The present invention relates to a film unit, and more particularly to an auto-process film unit ensuring even quality of prints.
2. Description of the Prior Art
There is known a type of film, which is commonly referred to as auto-process film, or by a similar appellation, and which, when employed in association with a special type of camera, makes it possible to obtain a useable photographic print almost immediately after the film has been exposed to light reflected from an object, processing and development of the film being effected automatically in the camera, and the film thus presenting the advantage that a photographer may obtain positive copies of photographed objects without further expense, or without the trouble of going to a separate establishment for film processing, and that a photographer may ascertain rapidly whether or not a particular shot has been taken satisfactorily. Successive frames of auto-process film are not provided in a continuous roll, but are constituted by individual film units, which are either completely unattached to one another, or linked by easily detachable tape, or similar means. Film units are packed in immediate succession to one another in a cassette, or pack, which is loadable in a camera, successive foremost film units being exposed, and then transferred from the pack and the camera, while being simultaneously processed. Each film unit comprises at least a photosensitive layer, which is exposable to produce a negative image of an object, a positive image layer, on which an image corresponding to the negative image may be formed by diffusion-transfer process, and a container, which holds a solution of processing chemicals, and which may be broken open by pressure means, for example, processing rolls provided in a camera, whereby the processing solution is spread between the exposed photosensitive layer and the positive image layer when the film unit is moved out of the camera. The photosensitive layer and positive image layer may be provided in a single sheet. In this case, however, each film unit must also include a lightproof layer, in order to prevent other film units from being partially exposed or blurred upon exposure of a foremost film unit. A more particular disadvantage associated with this kind of film unit is that, since the photosensitive layer and positive image layer are in very close proximity to one another, if not in immediate juxtaposition, and since processing of the exposed unit is required to be effected rapidly, unless special measures are taken, the processing solution may fail to be spread evenly through every part of the two layers, thus resulting in unevenness of quality in different portions of the completed copy. In order to overcome these disadvantages, it has been known to provide a film unit wherein a photosensitive layer and a positive image layer are constituted by independent sheets, which are initially provided separately, in forward and rear portions, respectively, of a cassette, and which are brought together to form a complete film unit only after exposure of the photosensitive sheet. However, this type of film unit has the disadvantage that construction of a camera which must be employed in association therewith is rendered very complex.
It is accordingly an object of the present invention to provide an auto-process film unit wherein even spreading of processing solution between photosensitive and positive image portions thereof is ensured.
It is another object of the present invention to provide an auto-process, film unit not requiring an incorporated opaque layer, and not requiring an associated camera of complex construction.